Peripheral arterial occlusive diesease is a common complication in diabetic patients. A prospective study of peripheral arterial disease in the diabetic and its progression over a five-year period is proposed. Three groups of subjects will be studied: 400 diabetic patients with and without symptomatic peripheral arteriosclerotic disease; l50 nondiabetic patients with symptomatic peripheral arterial disease; and l00 nondiabetic healthy control subjects (without peripheral arterial disease). Pertinent clinical data will be abstracted on each patient upon entry into the study. A limited physical examination will be carried out yearly and will include blood pressure determination in the arm, palpation and grading of peripheral pulses, presence or absence with grading of deep tendon reflexes at the knee and ankle and the presence or absence with grading of vibratory sense in the lower extremity. Transcutaneous Doppler ultrasound studies, ultrasound B-scanning of the femoral and carotid arteries, eye examination with retinal artery pressures, plasma glucose, serum lipids (cholesterol, triglycerides, and quantitative lipoproteins), platelet factor 4, platelet aggregation, and restocetin Willebrand factor assay will be measured at yearly intervals in these groups of subjects. Platelet survival studies will be carried out in 100 of the study subjects at baseline, one and five years of the study. The presence of and/or changes in these measurements will be compared in diabetic and nondiabetic groups and correlated with risk factors and diabetic treatment with standard "t" test and multivariant analyses. These observations will provide a description of the progression of peripheral arterial disease in the diabetic as compared to the nondiabetic and provide information as to what recorded changes over the period of the study best indicate progression or exacerbation of the arterial disease. The study should help determine how the presence or progression of arterial obstruction and/or plaque formation (as noted by these measurements) leads to significant ischemia and gangrene in the lower extremities of diabetic and nondiabetic subjects and what role platelet function has in the peripheral arteriosclerotic disease of the diabetic.